Portable phones have been widely accepted in the market, and various types of portable phones have been developed. Among these types, a compact and double-backed type is widely used. When the phone is not used, this double-backed type can be folded (double-backed) to be more compact.
The law effective since Jun. 2002 regulates the average amount of energy of radio wave transmitted from wireless devices such as a portable phone while a phone call is in progress. The law defines the average amount of energy (Specific Absorption Rate, hereinafter referred to as SAR) absorbed for six minutes into a specific portion (particularly to temporal region) of human body. It is thus required that the SAR be reduced to an amount not higher than a regulated amount.
Reduction of the SAR needs to reduce the electric power of radio wave radiated from the wireless device; however, the reduction of the power lowers the quality of a phone conversation.
Methods of reducing the SAR and yet maintaining the electric power radiated from wireless devices is disclosed in, e.g. Unexamined Japanese Patent Publication No. 2001-320459, and No. 2004-328346. The portable phones disclosed in the foregoing publications have the following structure: an upper housing and a lower housing of the portable phone are unfolded for starting conversation. In synchronization with this unfolding, a rod antenna falls down apart from the temporal region of the user, so that a peak of antenna current can be isolated from the temporal region for reducing the SAR. FIG. 5 shows a perspective view illustrating a conventional portable phone. In FIG. 5, the lower housing (not shown) includes antenna element 113, power feeder 112, lower circuit board 104 and the like. The upper housing (not shown) includes upper circuit board 105, flexible cable 106 and the like.
Running through a hollow section of the hinged section, flexible cable 106 is obliged to become close to the temporal region during a phone conversation. In the 2 GHz bandwidth employed in CDMA method, the peak of the antenna current exists not only in power feeder 112 but also it can exist in flexible cable 106. The distribution of antenna current changes, in general, in response to SAR, so that it is known that the presence of the peak of the antenna current in the temporal region increases the SAR. In other words, closer placement to the temporal region of flexible cable 106, in which the peak of antenna current exists, invites the higher SAR. The conventional method has thus encountered a difficult problem of reducing the SAR.